In relation to semiconductor devices, with the increasing demand for higher performance, higher functionality, and lower power consumption, circuit patterns have been increasingly miniaturized, leading to a significantly growing demand for removal of contaminant metals that would reduce the production yield. Therefore, it is preferable that contaminant metals such as iron or zinc are not contained in a chemical solution such as a protective film formation solution for imparting hydrophobicity to a substrate or a silicon wafer cleaning solution.
Such chemical solutions for use in the process of manufacturing semiconductor devices are cleaned beforehand to remove contaminant metals such as iron and zinc by way of a filter device or the like. The filter device ordinarily includes a filter medium with a porous membrane.
Since impurities such as metal ions are removed, porous membranes capable of removing minute substances such as nanoparticles are desirable. Nylon, polyethylene, polypropylene, PTFE, and the like are typically used as filter films capable of removing impurities from a chemical solution or a resin material for a semiconductor device or the like. For example, it is known that organic impurities can also be removed by way of a filter film of nylon or the like (for example, see Patent Document 1).
Patent Document 1: Japanese Patent No. 4637476